Stengil sheet and backing



Dec. 24, 1929. w. H. KURTH 1,741,029

STENCIL SHEET AND BACKING Filed Aug. 29,1927

Patented Dec. 24, 1929 UNITED, STATES PATENT OFFICE WILLIAM H. KUBTH, OFCHICAGO, ILLINOIS, ASSIGNOR TO THE HEYER DUPLICATOR CO. INC, OF CHICAGO,ILLINOIS, A CORPORATION OF ILLINOIS STENGIL SHEET AND BACKINGApplication filed August 29, 1927. Serial No. 216,077.

The present invention is directed to a stencil sheet and the backingprovided therefor which serves to mount and hold the stencil sheet inposition during the stencilling operation, and thereafter to secure thestencil sheet in position on the duplicating machine. In stencil sheetsand mountings of the character commonly in use, it is customary toemploy a stencil sheet provided with a coating consisting of celluloseester and Oll with a blue pigment included in the coating mixture toimpart a blue tint to the stencil sheet.

The completed stencil sheet, which is relatively transparent, comprisesa smooth and lustrous unbroken surface coating adapted to receive theimprint of the stencil, and when imprinted the continuity of the coatingWlll be broken or fractured along the stencilled lines, so that theselines will be rendered relatively opaque, and hence stand out as lighterlines on the colored ground surface of the stencil. This rendered theimprinted stencil legible as a lighter imprint against a darkerbackground, but in the use of a blue stencil sheet, the imprinted linesnevertheless lack sufficient contrast in color tint to render themeasily legible in the proof reading of the completed stencil sheets, sothat various expedients of one sort or another have been attempted torender the proof reading of the imprinted stencil sheets easier and lessfatiguing to the eyes of the proof reader. The present difficultyappears to be due to the fact that the use of a colored tint in thestencil sheet itself renders it impossible to secure a relatively whiteor uncolored stencil impression, since the impression itself partakes ofthe color tint employed in coating the stencil sheet, so that sharpcontrast in color tones is impossible.

The object of'the present invention is to produce a stencil sheet andthe associated mounting and impression sheets which will be so arrangedand colored as to provide for the securing of a stencil impression whichwill stand out in white letters against a black or other dark ground,thereby rendering the proof reading much easier and obviating thenecessity for the employment of especially illuminated table tops or thelike as aids in the proof reading.

In the drawing, the figure shows a stencil sheet with the impressionsheet and backing, the two upper sheets being partially rolled back toillustrate the manner in which the sheets are superposed upon oneanother.

The stencil sheet A is .formed of white or untinted and unsized tissuepaper, preferably the Japanese paper known as yoshino. This fibroustissue paper has applied thereto a stencil coating consisting preferablyof a thin layerof cellulose ester with an oil dispersed therein. Theingredients of a suitable coating are set forth and described in mcopending application Serial No. 152,806, filed July 6, 1926, althoughin the case of the present invention any suitable dry stencil coating ofthe character commonly in use at the present time may be employed,provided the coating contains no pigment or colorin matter which will,in any substantial degree, tend to color or darken the surface of thestencil sheet.

If white yoshino paper be employed as a base with an untinted coating ofthe charter indicated, the completed stencil sheet will have theappearance of a thin, white, fibrous, transparent sheet adapted whenlaid upon a colored backing to assume the color tone of the backingthrough the sheet with but slight reduction in the color tone.

The stencil sheet is secured by pasting along its upper edge to abacking B of relatively stiff and firm paper provided with the usualslots C near the upper edge for adjustment to the duplicating machine.Between the stencil sheet and the backing is interposed an impressionsheet D which, in the present instance, is also of yoshino tinted orstained black, although a very deep shade of some other color might beemployed. The impression sheet is provided in order to secure a moreperfect action in the coating of the stencil than can ordinarily besecured without extreme care if the stencil sheet were supporteddirectly against the relatively hard and firm surface of the backing. I

With the stencil sheet mounted and backed in the manner described thestencil coating type will strike upon and fracture the surface coatingof the stencil sheet in such a way as to break or pulverize the coatingmaterial, thereby completely destroying the transparent character of thecoating alongthe lines represented 'by the lettered forms of the t pe,so that the letters thus stencilled will appear as purely white lettersin sharp contrast. to the black or other dark ground afforded by theblack impression sheet or similar backing which shows through theuntinted transparent background of the stencil sheet. In short, theletters will stand out in sharp color relation by reason of the factthat where the letters are struck the stencil surface will reflect whitelight by reason of the opaqueness of the letters which will stand outagainst the dark ground occasioned by the visibility of the blackimpression sheet through the transparent, thin and untinted stencilsheet.

It will 'be understood that where reference is lnade to the transparencyof the stencil sheet, it is not intended to convey the impression thatthe sheet is completely transparent like window glass, but that itpossesses the relatively high degree of transparency characteristic of asheet of oiled tissue paper or oiled tracing paper, so that it willnotin any substantial degree lessen the blackness of the color tonetransmitted from the backing sheet through the body of the stencilsheet, so that the resulting effect is that of white letters sharplyimprinted upon a black ground which renders proof reading much easierthan in the case of stencil sheets in which a color tone is applied tothe stencil sheet itself.

In short. by employing a stencil coating of untinted materials upon awhite sheet of yoshino paper, and relying for the color tone entirelyupon a darkly tinted sheet underlying the stencil sheet, applicant isenabled to secure a completely white letter impression rather than atinted letter impression as heretofore, since the coating materialswhich display the impression are themselves untinted tinted, although,in this case, the advantages attendant the use of an impression sheetwill not be secured. Nor is it the intention in the claim where thestencil sheet and coating are referred to as being untinted to limit theclaim to an absolutely colorless or white sheet and coating, althoughanysubstantial employment of color tints will to that extentimpair theeffect which it is desired to secure by the omission of any colorwhatsoever as an ingredient of the coated stencil sheet.

I claim:

A stencil comprising a stencil sheet composed of untinted tissue 'paperhaving applied thereto an untinted stencil coating.

adapted to render the sheet transparent, said coating being adapted whenstencilled to have its coating rendered opaque by the impact to displaythe impacted portion ofthe coating as an opaque white stencil impressionin conjunction with a relatively firm mounting sheet to which thestencil sheet is secured, and an interposed relatively soft impressionsheet of darkly colored tissue paper adapted to'show through theunstencilled portions of the stencil sheet and invisible through thestencilled portions thereof to furnish a dark ground color for thedisplay of white stencilled impressions, substantially as described.

WILLIAM H. KURTH.

and produce a white effect as soon as their transparency is destroyed bythe impact of the stencilling type which disintegrates or pulverizes thesurface coating, and thus causes it to reflect white light which, inconjunction with the transmission of the color tone through thetransparent or unsten cilled portions of the sheet, produces the sharpcolor tone contrast characteristic of the present invention.

Although, it is preferred to use a black or darkly tinted impressionsheet behind the stencil sheet, it is not the intention to limit theinvention strictly to the use of such an impression sheet, since thecolor contrasts may be secured by super-posing the stencil sheetdirectly upon the hard surfaced backing or mounting sheet colored blackor darkly

